1. Field of the Invention
The present invention relates to a method for making band plate feeds deformed in section, which are varied stepwisely in thickness in their widthwise direction by cold rolling.
2. Prior Art
A sectionally deformed band plate feed 2 in which a metal plate feed 2a is stepped at 2b on its one side, as illustrated in FIG. 7 by way of example--hereinafter simply called a deformed band plate feed--finds use in wide applications such as connectors' contactors, relays' contactors and terminals for lapping connection.
Hitherto, such deformed band plate feeds have been typically made by the following techniques.
(1) Cutting
A metal band plate feed of rectangular shape in section is fed in its longitudinal direction, during which it is continuously cut in its preselected, widthwise positions by cutting or milling.
(2) Intermittent Rolling
As set forth in Japanese Patent Publication No. 53(1978)-27234, a metal band plate feed to be rolled is fed between a reciprocating flat roll and a mold provided on its side facing said flat roll with a projection or recess having a gradually increasing width, during which a certain pressure is applied to the flat roll to form on the band plate feed steps following the surface geometry of the mold.
However, a problem with the former cutting technique are that swarfs produced in cutting the metal band plate feed does not only make working environment worse but also lowers yields due to increased material losses. Another problem arises in connection with the quality of products, since they leave burrs, warps, etc. on their cut ends. The latter intermittent rolling technique, on the other hand, has difficulty in making variously deformed band plate feeds, since it needs costly molds. Another drawback with this technique is that the production efficiency is very low due to difficulty encountered in making deformed band plate feeds continuously.
In addition to the above techniques, there is another rolling technique in which one metal band plate feed to be rolled is fed between a pair of work rolls, at least one of which includes a barrel provided with a circumferential groove, thereby making a deformed band plate feed deformed. According to this technique, however, rolling is effected with a pair of rollers which are of the same diameter and the work rolls rotate at the same peripheral speed, so that the metal band plate feeds are largely elongated in the rolling direction. There is thus a large difference in length in the rolling direction between the rolled and unrolled portions, giving rise to undulations on the rolled portion. Such undulations become more marked at a higher reduction ratio.
In view of such problems of the prior art as mentioned above, a primary object of the present invention is to provide a method for efficiently making satisfactory band plate feeds deformed in section, which can be practiced with improved yields but without causing swarfs, burrs and undulations.